Polyacetal composition

ABSTRACT

A polyacetal composition having a good whiteness and an excellent heat stability comprises a polyacetal or copolyacetal; a hindered phenolic antioxidant; a nitrogen-containing compound; and a specified dihydroxydiphenyl or bisphenol.

United States Patent [191 Ishida et al.

POLYACETAL COMPOSITION Inventors: Shinichi Ishida; I-Iiromichi Fukuda,

both of Tokyo; Tadatoshi Matsuoka, Kawasaki, all of Japan Asahi Kasei Kogyo Kabushiki Kaisha, Osaka, Japan Filed: Apr. 8, 1974' Appl. No.: 459,186

Related US. Application Data Continuation-impart of Ser. No. 349,466, April 9, 1973, abandoned, which is a continuation of Ser. No. 1 17,760, Feb. 22, 1971, abandoned.

Assignee:

Foreign Application Priority Data May 28, 1970 Japan -45l7l [451 Sept. 2, 1975 [56] References Cited UNITED STATES PATENTS 3,190,852 6/1965 Doyle 260/4585 S 3,337,504 8/1967 Fisher 260/4595 R 3,378,518 4/1968 Doyle 260/4595 R 3,530,091 9/1970 Kitaoka et al.... 260/4585 R 3,743,614 7/1973 Wolters et al.... 260/18 R 3,787,353 1/1974 Ishii et al 260/459 P Primary Examiner-Melvyn I. Marquis Attorney, Agent, or Firm-Armstrong, Nikaido & Wegner [5 7] ABSTRACT A polyacetal composition having a good whiteness and an excellent heat stability comprises a polyacetal or copolyacetal; a hindered phenolic antioxidant; a nitrogen-containing compound; and a specified dihydroxydiphenyl or bisphenol.

31 Claims, No Drawings POLYACETAL COMPOSITION This application is a continuationin-part application of application, Ser. No. 349,466, filed Apr. 9, 1973, which in turn is a continuation of application, Ser. No. 1 17,760, filed Feb. 22, 1971, and which are both now abandoned.

This invention relates to a polyacetal composition having a good whiteness and an excellent heat stability.

It is known that the polyacetal resin (polyoxymethylene) can be prepared by polymerizing formaldehyde or its cyclic oligomer (trioxane or tetraoxane) and then subjecting the resulting polymer to various treatments of its terminal group, and a molding composition can be prepared by mixing an antioxidant, a heat stabilizer or other various stabilizers with the treated polymer.

In the preparation of the polyacetal resin, it is a necessary and important factor to incorporate various stabilizers to a polyacetal resin to improve the quality of the resin, in addition to the treatment of the terminal groups of the polyacetal resin, and heretofore various proposals have been made.

An object of the. present invention is to provide a composition of high molecular weight polyacetal resin having a remarkably improved whiteness and heat sta' bility.

Other object of the present invention is to provide a stabilizer capable of being added to a polyacetal resin to prepare a more stable composition than the conventional ones.

Further objects of the present invention will be apparent from the detailed explanation described hereinafter. i

As the stabilizer for polyacetal resin, there have generally been known phenolic compounds having complicated structure, aromatic amines, dicyandiamides, ureas, hydrazines, sulfur compounds and polyamides. To produce an excellent commercial polyacetal composition, these stabilizers have never been used alone, but have been usually used in combination of two kinds of stabilizers consisting of phenolic compounds, as an antioxidant, and such nitrogen containing compounds as polyamides or dicyandiamines, as a heat stabilizer.

We have made strenuous studies of a combination of the stabilizers for polyacetal resin, and as a result have found a novel combination of the stabilizers showing quite excellent synergistic effect and accomplished the present invention. More particularly, we have found that a polyacetal composition having an unexpected heat stability can be obtained by using, as a third component, specified dihydroxydiphenyls or bisphenols together with the above two kinds. of stabilizers.

It has been already well known that various phenolic compounds are generally used as a stabilizer for the polyacetal resin. However, all kinds of phenolic compounds are not always useful as the stabilizer. U.S. Pat. No. 2,966,476 discloses a suitable phenolic compounds having the following formula:

OH OH r n 5 X 6 6 6 6 wherein R is hydrogen or alkyl of l to 3 carbon atoms;

and v R is alkyl of l to 5 carbon atoms, that is, the socalled hindered phenols. For example, 4,4-butylidenebis-(3-methyl-6-tertbutylphenol) or 2,2-methylenebis-(4,6-dimethylphenol), etc. have been particularly recommended. These compounds are special bisphenols characterized by their functions for protecting the oxidation and the discoloration of polyacetal resin. Other phenolic compounds are said to lack in either or both of said characteristics.

It is also known that the amine type stabilizers show an excellent stabilizing effectfor polyacetal resin, but they bring about a discoloration to brown or black when used (See U.S. Pat. No. 2,966,476). Further, such well-known antioxidants as urea or hydrazines also give discolored products.

In addition, it is well known that some kinds of specific polyamides are very effective as a stabilizer for polyacetal resin, because their heat stabilizing effect is relatively reliable and long lasting. However, all kinds of polyamides are not always effective. For example,

according to U.S. Pat. No. 2,993,025, the terpolymer consisting of 35 percent hexamethylene adipamide, 27 percent hexamethylene sebacamide and 38 percent caprolactam shows a good heat stabilizing effectamong the polyamides.

Even said copolyamide showing the abovementioned excellent heat stability still has great defects. One of the defects is a discoloration. That is, when it is admixed with polyacetal resin, resultant resin composition discolors with elapse of time and the discoloration is remarkable under high temperatures such as molding temperatures.

However, it is found that such disadvantages have been overcome and an unexpected, remarkable stabilization effect can be attained by the present combination of stabilizers,

Thus, according to the present invention, at least one compound is selected from each of the following three groups. The compounds thus selected are admixed with polyacetal resin to prepare the polyacetal composition of the invention. The groups are:

Group 1 Hindered phenolic compounds Group 2 Nitrogen-containing compounds Group 3 Dihydroxydiphenyls or bisphenols.

According to the description of the specification of U.S. Pat. No. 2,966,476, which is concerned with the stabilization of polyacetal resin by way of a phenolic antioxidant, all hindered phenolic compounds belonging to Group I cannot be used in combination with terpolyamide belonging to Group 2, because of poor stabilizing effect and discoloration. Representative examples of such hindered phenolic compounds include 2,2- '-methylene-bis-(4-methyl-6-tert. butylphenol), 2,2- methylene-bis-( 4ethyl-6'tert.butylphenol 4,4 methylene-bis-( 2,6-di-tert.butylphenol 2,2 butylidene-bis-( 4-tert.butyl-o-methylphenol) and compounds having following formula:

(wherein R is alkyl of l to 5 carbon atoms and X is wherein R is alkyl of l to 5 carbon atoms, and X is an hydrogen, hydroxy or alkyl of 1 to 5 carbon atoms) integer of l to 6, preferably 2; for example, pentaeryth- However, it is surprising that the addition of dihyrityltetra-2-(3,5-di-tert.butylphenyl)propionate; the droxydiphenyls or bisphenols or derivatives thereof befollowing formula (IV):

(CH C R on on q C (CH 3 longing to Group 3 as a third component makes it efwherein R is hydrogen or methyl, and feetive to use such hindered phenolic compounds be- R is hydrogen or alkyl of l to 4 carbon atoms; for longing to Group 1 together with the compounds beexample, l,3,5-tris-(3',5'-di-tert.butyl-4- longing to Group 2. hydroxybenzyl)2,4,6-trimethylbenzene; the following Thephenolic compounds of Group 1 relevant to one formula (V): t component of the stabilizers of the present invention NHH C I are so-called hindered phenols represented by the fol- 1 2 CH Ni-LR lowing formula (I):

03 on H0 12 0H (V) 5 wherein 6 R is hydrogen, alkyl of l to 5 carbon atoms or alkenyl of 3 to 4 carbon atoms; and wherein R is hydrogen or alkyl of 1 to 3 carbon atoms;

R is alkylidene of l to 8 carbon atoms; for example, 6,6'-methylene-bis (a,a-diamino-2,4-xylenol), 6,6 -ethylidene-bis (a,a-diamino-2,4-xylenol 6,6'-propylidene-bis (a,oz'-diamino-2, 4-xylenol), 6-6'-butylidene-bis (a,a'-diamino-2,4-xylenol) and and R is alkyl of l to 5 carbon atoms; for example, 4,4- ethylidene-bis-( 2-methyl-6tert.butylphenol 4,4- butylidene-bis-(3-methyl-6-tert.butylphenol) or 2,2-

tg i -gi -g3 ::yi-g-i rzyipg ii- 40 4,4'-butylidene-bis (a,a-diamino-2,4-Xylenol); me yene-is- -me y--er.uypeno, h f f v1; methylene-bis-(4-ethyl-6-tert.butylphenol), 4,4- and t e O owmg ormu methylene-bis-( 2,6-di-tert.butylphenol) and 2,2 OH butylidene-bis-(4-tert.butyl-6-methylphenol); the fol- R13 lowing formula (II): 5 13 l v x R 7 wherein 7 R is alkyl of l to 5 carbon atoms; and

X is hydrogen, hydroxy, or alkyl of l to 5 carbon H atoms; for example: 2,6-d1-tert.butylphenol, 2,6-di- 1 C CH2 CH C 3 tert.butyl-4-methylphenol; 2,6-di-tert.butylhydroquinone and 2,6-di-tert.amylhydroquinone. R Further, in addition to these phenolic compounds, the formates of the compounds as represented by the 7 formulae l-lII and V-Vl, for example, 2,6-di-tert.butyl- 0d 7 4-methyl-l-formyloxybenzene, 4,4'-butylidene-bis(3- methyl-o-tert.butyll -formyloxybenzene) and l l ,3- tris( 2-methyl-4-formyloxy-5-tert.butylphenol )butane, may be used.

Th compounds of Group 1 are so-called hindered wherein R is alkyl of l to 5 carbon atoms; for example, 0 l, l ,3-tris-( 2-methyl-4-hydroxy-5-tert.butylphenyl )butane; the following formula (ill):

\I phenols whose antioxidant properties for various poly- 3 3 O mers have been well recognized, that is, the phenolic u C compounds whose at least one hydrogen atom at the )-C-O-CH 4 ortho positions to the hydroxyl group is substituted by x x alkyl group. Quite different from other polymers, polyacetal resin (III) is required to be stabilized by means of a nitrogencontaining compounds. The stabilizing effect thereof cannot be explained clearly, but there is such a hypothesis that the nitrogen-containing compounds act as an acceptor for monomeric formaldehyde or for a very small amount of acids present or formed in polyacetal resin.

The nitrogen-containing compounds of Group 2, used as one component of the stabilizers of the present invention, include polyamides [for example, terpolyamides consisting of hexamethylene adipamide, hexamethylene sebacamide and caprolactam (U.S. Pat. No. 2,993,025); polyamides consisting of caprolactam and hexamethylene sebacamide (J. Poly. Sci.2, 412 (1947)], polyester amides prepared from caprolactone and caprolactam (.lap. Pat. No. 573,915 and U.S. Pat. No. 3,592,873); polyester amides described in the claim of U.S. Pat. No. 3,355,514; polycondensates prepared from dicarboxylic acid dihydrazide or substances capable of yielding a dicarboxylic acid dihydrazide, urea and aliphatic diamines (Dutch Pat. No. 6,818,620); uracyls, amidines, cyanoguanidines, polyurethanes, polyureas, polyamide-ureas, polyurethaneamides, and polyaminotriazols, and copolymers or mixture of these compounds. Other known synthetic polyamides and copolyamides are also useful.

According to the present invention, the nitrogencontaining compounds prepared by polycondensating dicarboxylic acid dihydrazide, urea and diamine are particularly excellent.

The compounds of Group 3 used as one component of the stabilizers of the present invention are dihydroxy diphenyls or bisphenols compounds as represented by the following formulae (VII) and (VIII), respectively:

HOQQT (VII) wherein R is hydrogen or alkyl group having I to 5 carbon atoms, preferably hydrogen, and

(VIII) pounds of Group 1 and said nitrogen-containing compounds of Group 2 at the same time, excellently stabilized polyacetal compositions may be obtained, as compared with the two component stabilizers consisting of the compounds of Group 1 and Group 2, or Group 1 and Group 3, or'Group 2 and Group 3. i

It is surprising that among the compounds of Group 3, there are included those phenolic compounds which are not the so-called hindered phenols; namely, they exert a high synergistic effect by using together with the compounds of Groups 1 and 2. The compounds of Group 3 are different from phenolic compounds of Group 1.

In the present invention, phenolic compounds of Group 1 are used in an amount of 0.01 to 3 percent by weight on the basis of the weight of polyacetal. The use of a large amount of said phenolic compounds gives no trouble to the stabilization effect, but from the economical view point 0.01 to 0.5 percent by weight of the phenolic compounds are preferably used. On the other hand, nitrogen-containing compounds of Group 2 are used in an amount of 0.1 to 10 percent by weight, preferably 0.1 to 3 percent by weight on the basis of the weight of polyacetal. Further, dihydroxydiphenyls or bisphenol compounds of Group 3 are used in an amount of 0.001 to 3 percent by weight on the basis of the weight of polyacetal.

The polyacetal whose heat stability can be remarkably improved by the application of the present invention includes polyoxymethylene homopolymer having a degree of polymerization of 500 or more, prepared by polymerizing formaldehyde or its cyclic oligomer and then subjecting the resulting polymer to end capping such as etherifying or esterifying and polyoxymethylene copolymers having the same degree of polymerization as mentioned above, prepared by copolymerizing formaldehyde or its cyclic oligomer with a comenomer capable of copolymerizing with formaldehyde or its cyclic oligomer and then subjecting the resulting copolymer to end capping such as etherifying, esterifying or converting the unstable terminal oxymethylene units to units other than oxymethylene units by the heat treatment or hydrolysis treatment. Representative examples are polyoxymethylene diacetate, polyoxymethylene dimethylether, polyoxymethylene diethylether, copolymers of trioxane and dioxolane, and copolymers of trioxane and styrene.

Generally, it is well known that the stabilizers for polyoxymethylene homopolymer are often found quite or almost unsuitable for the stabilizers for polyoxymethylene copolymer, and further that the reverse cases are often encountered. Surprising enough, however, the novel combination of the stabilizers of the present invention shows a large synergistic effect upon the stabilization of any of polyoxymethylene homopolymers and polyoxymethylene copolymers.

Now, the present invention will be explained, referring to examples, but the present invention will not be restricted to these examples.

In the following examples, all percent and part show percent by Weight and part by weight, respectively.

R (percent) shows a residual percentage of the polyacetal composition after the heat treatment of the polyacetal composition at 222C in the air for 60 minutes, and the resistance to light shows a change after the irradiation for 300 hours by the standard fade meter.

Z value shows the degree of whiteness of the polyacetal measured by l-lunters color-meter. K value shows the reaction rate constant of polymer for thermal degradation measured by the method described in U.S. Pat. No. 2,964,500 and 2,998,409.

EXAMPLES 1- l 2 Specified amounts of various stabilizers as shown in Table l are added to and mixed with polyoxymethylene diacetate prepared by polymerizing formaldehyde and acetylating the resulting polymer with acetic anhydride (reduced viscosity measured at 60C in a solution mixture of equal amounts of tetrachloroethane and pchlorophenol: 2.00 and K :0.05), and then the mixture is mixed for 20 minutes by means of a double cone blender. The resulting mixture is vacuum-dired at 60C for 6 hours. Then, a molded plate having a thickness of 0.5 mm is prepared by a test hot press at a temperature of 190C, and subjected to measurement of the heat stability. The results are shown in Table 1 together with the results of comparative tests.

Table 1 Comparative Name of additive Test Amount of additive added. "/1

R( 71 Resistance compound to light 4,4-dihydroxydiphenyl- 2.2'propane 0.1 85.3 No change 2.6-di-tert.butyl-4- methylphenol 4.4-butyIidene-bis- (S-methyI-fa-tcn. hutylphenol) 2,2'-methylenc-bis- (4-mcthyl-6-tert. butylphenol) Slightly 90. 2 red 1.1 .3-tris(2 -methyl- 4-hydroxy-5-tcrt. butylphenyl )butane 92.0

l 3,5-trimcthyl- 2,4 6-tris-( 3.5-ditcrLbutyl-4-hydroxybenzyhbenzenc 89.5

2,2 '-metl'iylcnc-his- (4-methyl-6-tert.- hutylphenol) formate Slightly Terpolyamidc (A) 86.5 yellow Nitrogen-containing compound (8) 9 l .5 No change Polyester amide (C) 89.3

Changed to Diphcnylamine 90.3 brown 4,4'-dihydroxydiphenyl 2,2-propanc Terpolyamidc (A) Slightly yellow Diphenylamine Terpolyamide (A) 1.

Changed to brown 2,6-di-terLhutyl-4- mcthylphenol Terpolyamide (A) Polyester amide (C) 96.5

B: polycondensate of dicarboxylic acid dihydrazide,

hexamethylene diamine and urea; that is, a nitrogen-containing polycondensate having a colorless, transparent appearance and a softening point of 140C to 160C, obtained by placing 20 parts of sebacic acid dihydrazide, 20 parts of adipic acid dihydrazide, 15 parts of hexamethylene diamine and 60 parts of urea in a 300cc, three-necked flask, melting the mixture at 200C in a nitrogen gas stream with stirring to effect reaction while heating the mixture for 120 minutes, then connecting the reaction system to a vacuum line under 0.5 mm Hg and further heating the mixture at 200C for 240 minutes to effect the reaction.

C: polyester amide, that is, a polyester amide having a melting point of about 200C, prepared by dissolving 90 parts of caprolactam and 10 parts of caprolactone in 400 parts of dehydrated toluene, effecting polymerizing at 110C for hours using 3 percent by mole of ethylmagnesium bromide and 3 percent by mole of N-acetylcaprolactam as a catalyst on the basis of the monomers, washing the resulting white powders with an aqueous 1 percent hydrochloric acid solution, repeating water washing until the washings exhibit the neutrality and drying the washed powders.

EXAMPLE 13 129 parts of tetradecanedioic acid dihydrazide, 30 parts of hexamethylenediamine and 50 parts of urea are placed into a three-necked flask having a capacity of 500 cc and subjected to reaction by heating at 210C in a nitrogen gas stream for 120 minutes. In another threenecked flask having a capacity of 300 cc, 100 parts of sebacic acid dihydrazide, 25 parts of tetramethylene diamine and 40 parts of urea are subjected to reaction by heating at 210C in a nitrogen gas stream, and the resulting transparent molten product is added to the former flask. The mixture is heating at 210C under a reduced pressure of 0.5 mm Hg for 300 minutes to complete the reaction, whereby a white, semi-transparent. nitrogen-containing polycondenstate is obtained.

The esterified polyoxymethylene homopolymer used in Example ll2 is mixed with 0.8 percent of said nitrogen-containing polycondenstate, 0.1 percent of 4,4-dihydroxydiphenyl-2,2-propane, and 0.5 percent of 2,6-di-tert.butyl-4-methylphenol by means of a Henschcl mixer having a capacity of 150 I at 40C for minutes.

Then, pelletizing is carried out by means of an extruder having a cylinder temperature of 200C. R (percent) and Z of the pellets are 99.3 percent and 99, and R (percent) and Z of the pellets obtained by four repetitions of the pelletizing under the same conditions are 98.7 percent and 97, respectively.

On the other hand, the same polyoxymethylene homopolymer is mixed with 1.0 percent of terpolyamide (A) consisting of 35 percent hexamethylene adipamide, 27 percent hexamethylene sebacamide and 33 percent caprolactam, 0.1 percent of diphenylamine and 0.5 percent of 4,4'butylidene-bis(3-methyl-6- tert.butylphcnol) for comparison. Then pelletizing is carried out in the same manner as described in the above Example. R (percent) and Z of the pellets are 98.5 percent and 98 and R (percent) and Z of pellets obtained by four repetitions of the pelletizing under the same conditions are 97.0 percent and 92, respectively.

EXAMPLE 14 About 0.1 g of boron trifluoride gas is added to a flask containing 55 cc of isobutylene and being kept at C, and dehydrated formaldehyde vapor is passed through the flask, while stirring the mixture for about 10 minutes. The resulting product is filtered and dried. The thus obtained polyoxymethylene copolymer is treated in anhydrous acetic acid in the presence of sodium acetate, whereby the copolymer is acetylated.

The resulting esterified copolymer is mixed with 0.8 percent of a nitrogen-containing compound (B), 0.05 percent of 4,4'-dihydroxydiphenyl-2,2-propane and 0.4 percent of 2,6-ditert.butyl-4-methylphenol, and then the mixture is extruded from a small extruder at a cylinder temperature of 195C to prepare pellets. The heat stability, R (percent) of the pellets is 99.3 percent.

EXAMPLE 15 A mixture of 500 parts of polyoxymethylene copoylmer containing 3.1 percent of the monomer units derived from dioxolane, 1000 parts of water and 150 parts of triethanolamine are heated in a tightly sealed autoclave at to C for 2 hours 15 minutes. At the end of said period, the autoclave is cooled to room temperature and opened. The resulting copolymer is washed with acetone and successively with hot water, and then dried.

The resulting copolymer is mixed with 0.1 percent of dicyandiamide, 0.3 percent of 2,2-methylene-bis(4- methyl-6tert.butylphenol) formate, and 0.08 percent of 4,4-dihydroxydiphenyl-2,2-propane, and then the thus obtained mixture is pulverized in a heating room having a mixer provided with sigma-type blades at a temperature of 200 to 205C for 45 minutes. The heat stability, R (percent), of the pulverized composition is 99.4 percent and the whiteness value, Z, is 99, respectively. The R (percent) of the composition containing no 4,4'-di-hydroxydiphenyl-2,Z-propane is 98.0 percent in the above example.

EXAMPLE 16 230 parts of sebacic acid dihydrazide is placed in a three-necked flask having a capacity of 1,000 cc, and heated to 200 to melt while stirring the content in a nitrogen stream. Then, 30 parts of urea and l 16 parts of hexamethylenediamine are added thereto and subjected to reaction at a reaction temperature of C by heating for 300 minutes. Colorless, transparent reaction solution has a gradually increased viscosity, and at the final stage of the reaction, the solution becomes turbid and then turns to a semi-transparent, viscous solution. Then, the reaction system is broughtinto a vac uum of 1 mm Hg, and the reaction temperature is increased to 200C. Then, the reaction is further carried out by heating for 300 minutes to complete the mac tion, whereby 220 parts of white block polycondensate having a elemental analytical values of 53.71 percent carbon, 7.69 percent hydrogen and 24.55 percent nitrogen is obtained.

The resulting polycondensate softens and melts at about C, and a transparent, colorless, beautiful film or sheet can be prepared by compression molding using hot presses. The polycondensate can be also made into a film by dissolving the same in dimethylsulfoxide or methanol and evaporating the solvent to dry ness, and also the polycondensate can be finely pulverized by pouring the same into such a non-solvent as dioxane. The specific viscosity of the polycondensate measured at 30C in methanol is 0.30.

Polyoxymethylene diacetate having an intrinsic viscosity of 2.10 and K of 0.03 is mixed with 0.8 percent of said finely pulverized polycondensate powders, 0.5

Rcucti m c )m 'lSlllO W it nus percent of 4,4'-butylidene-bis(3-methyl-6- Adipic f z ifi h I tert.butylphenol) formate, 0.1 percent of 4,4'- 5 amplcs ucid di Urea diuminc Rm) dihydroxydiphenyl-2,2-propane and 0.2 percent of titahydmm nium white (rutile type), and the resulting polyacetal 2g composition is injection-molded at 190C, whereby a 5 :5 9:; thin sheet having a thickness of 3 mm is prepared. I39 6 99-08 The sheet is heat-treated in air at 222C for 120 min- 10 utes, and as a result 1.3 percent of the weight is lost. EXAMPLE 30 ztz gz z zg 1 :65 fi g zi is glz ggi treatment A mixture of 258 parts of tetradecanedioic acid dihy- The molded sheet is pulverired and again injectiondrazlde parts of39431543-ammopropyn'z4's'H?- l5 tetraoxaspiro-[5,5]-undecane and 60 parts of urea molded into the sheet. Even 11" such operation 15 reheated in a thrccmecked flask having a capacity of pcated four tlmes no colormg observed 1,000 cc at 190C with stirring. The reaction mixture EXAMPLES 17 29 gradually turns to a viscous molten solution, while evolvin a as. Then, the reaction s stem is brou ht A rmxtur of P afhplc l f and 20 into a r duc ed pressure of 1 mm Hg, and the rcacti on fnethylenefllamme h avmg a composmon who i shown is carried out at 210C for 120 minutes to complete the m Table 2 Placed m threefnecked flask half/mg a reaction, whereby 360 parts of a nitrogen-containing Pacity of 300 cc P wlth powerful surfer and polycondensate having a white and semi-transparent heated to 200C in a nitrogen gas stream to melt. The appearance is obtained reaction temperature is lowered to 170C and the reac- Polyoxymethylene diacetate having an intrinsic tion is further carried out at 170C for 300 minutes. cosity f1 8() and [(222 f ()2 i l mixed with 1 The reaction mixture turns to a Colorless, Semicent of the resulting polycondensate of tetradecaneditransparent y Viscous oic acid hydrazide and 3,9 -bis-(3-aminopropyl)- Then, the reaction system is connected to a vacuum 2 4 3 1 i 5,5] undecane, Q3 percent f line of 1 mm Hg, and is Subjected to reaction y heating 2,6-di-tert.butyl-4-methylphen0l and 0.1 percent of 4,- at 200C for further 90 minutes, whereby nitrogen- 4'-dihydroxydiphenyl-2,2-propane and the mixture is containing polycondensates having various composii j ti ld d t 190C, he b a old d piece tions are obtained. having a good whiteness is obtainedThe heat stability Polyoxymethylene diacetate having an intrinsic visof the i ce i 99.36, cosit of 1.60 and K of 0.03 is mixed with 1.0 percent of ari y of these nitrogen-containing polycondensates, EXAMPLES 31743 0.2 percent of 2,2-methylene-bis(4-methyl-6- 174 parts of adipic acid dihydrazide is placed in a ter -buty p e and PefCCnt 0f three-necked flask having a capacity of 1,000 cc and dihydr Xydi henyI-Z,2-propane, and the resulting polyheated to 200C in a nitrogen gas stream with stirring acetal composition is injection-molded at 195C, 40 to melt the same. Then 60 parts of urea and 1 16 parts whereby test pieces are made in order to measure heat of hexamethylenediamine are added thereto, and the stability. The results are shown in Table 2. reaction temperature is lowered to 170C and the reac- Table 2 tion is carried out for 5 hours with stirring.

The resulting pre-condensate is divided into 12 parts and then each part is further heated under a reduced Reaction composition (g) whiteness Adipic Hexamcthylene value Z pressure of 1 mm Hg under the conditions as shown in amplcs acid s (amine m Table 3. The results are shown In Table 3.

hydrfllidc Polyoxymethylene diacetate having an intrinsic vis- I7 43 30 29 9936 98 cosity of 2.10 and K of 0.03 is well mixed with 0.8 is 46 32 24 99.30 98 50 percent of each of the nitrogen-containing polycondenl3 :8 g; :2 sates as shown in Table 3. 0.2 percent of 2,6-di-tert.bu- E 37 7 99:00 97 tyl-4-methylphenol and 0.07 percent of 4,4- 22 62 21 33 99.40 99 dihydroxydiphcnyl-Z,2-propane, and the resulting polygi acetal composition is extruded at 195C to pelletize the 25 79 27 11 99.10 as 55 same. The result is shown in Table 3.

Table 3 Condensation Product condensate condition Composition Example Temperature Time Yield Elemental Whitcncss (C) (hr) ('7( arlisily/lsis Appearance R('/1 value 2 31 190 I 25.1x white. scmi- 99.30 97 transparent 32 3 63. 25.7 colorless, 99.43 98 transparent 33 190 i (10 25.9) colorless. 99.28 98 transparent 34 200 1 62 25.79 white, semi- 99.20 ex Table 2-Continued transparent Condensation Product condensate condition Composition Example Temperature Time Yield Elemental whiteness (C) (hr) 7!) analysis Appearance R('7r) value Z 200 3 60 26.02 colorless. 99.21 99 transparent 36 200 5 59 26.50 colorless. 99.05 99 transparent 37 220 0.5 65 25.20 white. semi- 99.0 98

transparent 38 220 l 63 25.98 colorless. 99.40 99 transparent 39 220 3 58 25.88 colorless. 99.41 99 transparent 40 220 5 56 25.73 colorless. 99.36 99 transparent 41 240 0.5 53 25.80 colorless. 99.36 99 transparent 42 240 l 53 25.78 colorless. 99.48 99 transparent 43 240 2 51 25.86 colorless. 99.49 99 transparent EXAMPLE 44 tert.butyl-4-methylphenol). and 0.1 percent of 4,4-

17.4 parts of adipic acid dihydrazide, 11.6 parts of hexamethylenediamine and 7.1 parts of biuret are placed in a hard glass ampule. and heated at 190C under an atmospheric pressure for 240 minutes. Then, the ampule is connected to a vacuum line of 1 mm Hg and the heating is further carried out at 220C for 120 minutes, whereby 22 parts of a white, nitrogencontaining polycondensate having an elemental analysis of 50.55 percent carbon, 7.20 percent hydrogen and 27.80 percent nitrogen is obtained.

Polyoxymethylene diacetate having a softening point of 175C and an intrinsic viscosity of 2.10 is mixed with 0.8 percent of said polycondensate, 0.4 percent of 2,6- di-tert. butyl-4-methylphenol and 0.1 percent of 4.4-dihydroxydiphenylmethane and the resulting polyacetal compositionis injection-molded at a cylinder temperature of 195C and a mold temperature of 100C under an injection pressure of 1,000 kg/cm whereby a thin sheet having a thickness of 3 mm is prepared. The sheet is heat-treated, as a test piece, in air at 220C for 120 minutes, and as a result 1.7 percent of the weight is lost. The whiteness value, Z, is 99. The composition after said heat treatment at 220C is molded into a film under a pressure of 200 kg/cm by means of a test hot press at 190C, and the whiteness value. Z, of the thus obtained film is 98.

EXAMPLE 45 Polyoxymethylene diacetate having an intrinsic viscosity of 180 and K of 0.04 is mixed with 0.7 percent of the nitrogen containing polycondensate described in Example 3, 0.3 percent of 2,2-butylidene-bis-(2- dihydroxydiphenyl-2,Z-propane, and the resulting polyacetal composition is extruded at a cylinder temperature of 195C by means of a small test extruder having a cylinder inside diameter of 20 mm to pelletize the same. Then, the thus obtained polyacetal pellets are heat-treated in air at 222C for 120 minutes, whereby 1.0 percent weight is lost, but no discoloration is effected almost at all. On the other hand, the same polyoxymethylene homopolymer is mixed with 0.7 percent of the same nitrogen cntaining polycondensate, 0.3 percent of 2,2 -butylidene-bis-( 2-tert. butyl-4- mcthylphenol) and 0.1 percent of 4,4'-dihydroxy-3,3'- dimethyldiphenyl-2,2-propane and the resulting polyacetal composition is extruded in the same manner as described above. The weight loss of the obtained polyacetal pellets is 1.9 percent.

EXAMPLE 46-56 Various kinds of dicarboxylic acid dihydrazides, diamines and urea or urea derivatives as shown in Table 4 are subjected to reaction according to the same procedure as described in Example 1, whereby the respective nitrogencontaining condensates are synthesized.

Polyoxymethylene diacetate having an intrinsic viscosity of 2.10 and K of 0.02 is well admixed with 0.7 percent of each said nitrogen-containing polycondensate, 0.4 percent of 2,6-di-tert.butyl-4-methylphenol and 0.05 percent of 4.4-dihydroxydiphenyl, and the resulting polyacetal composition is extruded at a cylin der temperature of 190C to pelletize the same. The resulting pellets are subjected to heat stabilization test, and the results are shown in Table 4.

Table 4 Components of charge Polyacetal composition (/r by mole) Softencomposition Example dicarboxylic acid Urea or Yield ing Appearance whiteness No. dihydrazide diamine urea dc- (/1 point R(/1 value rivativcs ((7) 7.

46 Sehacic acid Bisamino- Urea 50 62 -130 colorless, 99.20 99 dihydrazide 25 propylether transparent 25 47 Suheric acid Hexamethyl- Urea 50 64 -160 Colorless. 99.38 99 dihydrazide 30 ene diaminc transparent 20 48 Oxadivaleric Penta- Urea 40 67 -180 colorless. 99.00 98 acid dimethylcnetransparent hydmzide 40 diaminc 20 Table 4 Continued Components of charge Polyacctal composition (7! by mole) Softencomposition Example dicarboxylic acid Urea or Yield ing Appearance whiteness No. dihydrazide diamine urea dc- (71 point R('/r value 4 rivatives (C) Z 49 Cyclohexanc- Hexa- Urca 45 60 140-160 colorless, 99.10 98 dicarboxylic acid methylencsemidihydrazide 35 diamine 20 transparent 50 Sebacic acid Hexa- Ethylcnc 62 1701 80 colorless. 99.20 99 dihydrazide 30 methyleneurea 45 transparent diamine 51 Adipic acid Hexa- Biurea 59 180-190 colorless. 99.31 98 dihydrazide 25 methylene- 50 transparent diamine 25 52 Sebacic acid Tetra- Mcthylenc- 60 140-160 colorless, 99.00 99 dihydrazidc methylene bisurea transparent diaminc 25 45 53 Azelaic acid Hexa- Urea 59 140480 colorless, 99.30 99 dihydrazide 40 methylenetransparent diamine 20 54 Suheric acid Nona- Thiourea 62 160-190 white, semi- 99.10 97 dihydrazide 33 methylene- 47 transparent diaminc 20 5S Adipic acid Nona- Ethylene- 58 180-200 white, semi- 99.08 97 dihydrazidu 35 methylenethiourca transparent diamine 20 56 Dimeric acid Hexamethy Urea 170-120 slightly 99.00 97 dihydrazide 25 methyleneyellow,

diamine 25 transparent EXAMPLE 57 flask having a capacity of 300 cc provided with a vigor- 7.5 parts of oxalic acid dihydrazide, 8.6 parts of decamethylenediamine and 6 parts of urea are placed in a hard glass ampule, and heated at 210C in a nitrogen gas stream for 120 minutes to effect reaction. Then, the ampule is connected to a vacuum line of 0.5 mm Hg and the reaction temperature is elevated to 240C and the ampule is heated further for 180 minutes. Initially, the reaction is in a white block form, but starts to melt after 120 minutes of the reaction time under a reduced pressure, and turns to a colorless, transparent and very viscous mixture. Finally, 13 parts of a colorless, transparent nitrogen-containing polycondensate is obtained. The nitrogen content thereof is 21.08 percent by analysis. The resulting polymer can be formed in a beautiful film by pressing at 200C under a pressure of 250 kg/cm by means of a test hot press.

Polyoxymethylene diacetate having an intrinsic viscosity of 2.30 and K of 0.07 is mixed with 0.8 percent of said nitrogen-containing polycondensate, 0.3. percent of 2,6-di-tert.butylhydroquinone and 0.2 percent of 4,4'-dihydroxydiphenyl, and the resulting polyacetal composition is extruded at a cylinder temperature of 195C by means of a small test extruder having a cylinder inside diameter of 20 mm to pelletize the same. Then, the thus obtained polyacetal pellets are heattreated in air at 222C for 120 minutes, whereby 1.2 percent weight is lost, but no discoloration is effected almost at all.

Said polyacetal pellets are extruded repeatedly five times under the same cylinder condition to pelletize the same. The whiteness of the resulting pellets is not changed even after the fourth repetition, and the every Z values are all 98. After the fifth pelletization, the Z value turns to 97.

EXAMPLE 58 17 parts of adipic acid dihydrazide, 16 parts of malonic acid dihydrazide, 40 parts of isophoronediamine and parts of biuret are placed in a three-necked ous stirrer, and heated and molten at 200C in a nitrogen gas stream, and further subjected to reaction by heating at the same temperature for 300 minutes. The reaction mixture is solidified while evolving the gas. Then, the reaction system is connected to a vacuum line of 1 mm Hg and the mixture is further subjected to reaction by heating at 230C for minutes. The reaction is gradually molten and turns to a viscous, colorless transparent molten solution, whereby 93 parts of a colorless, transparent, glass-like, nitrogen-containing polycondensate having a nitrogen analysis of 20.68 percent is obtained. lts softening point is C.

Polyoxymethylene dimethylether having an intrinsic viscosity of 2.10 and K of 0.01 is mixed with 0.9 percent of said nitrogen-containing polycondensate, 0.4. percent of 2,2-methylene-bis(4-methyl-6- tertbutylphenol) and 0.1 percent of 4,4-

clihydroxydiphenyl-Z,2-propane. The resulting polyacetal composition is extruded at a cylinder temperature of 195C by means of a small test extruder having a cylinder inside diameter of 20 mm to pelletize the same, whereby the pellets having a whiteness value, Z, of 99 are obtained. Then the pellets are heat-treated in air at 222C for 120 minutes, whereby 1.0 weight is lost, but no discoloration by the heat treatment is observed almost at all.

EXAMPLES 59-62 Various polyoxymethylene copolymer as shown in Table 5 are mixed with 0.8 percent of a nitrogencontaining polycondensate synthctizcd from adipic acid dihydrazide, urea and hexamethylenediaminc in the same manner as in Example 1 and having an elemental analysis of 56.12 percent carbon, 8.66 percent hydrogen and 20.34 percent nitrogen, 0.3 percent of 2,2-methylene-bis( 4-mcthyl-6-tert.butylphenol) and 0.1 percent of 4,4-dihydroxydiphcnyl-2,2-propane. and the resulting polyacetal composition is extruded at a cylinder temperature of C to pelletize the same. The resulting pellets are subjected to the heat stabiliza- Table dihydroxydiphenyl-2,2-propane. The resulting polyacetal composition is injection-molded at 195C under a pressure of 800 kglcm whereby a molded article having a good whiteness and a lustrous surface is obtained.

5 The heat stability, R (percent) of the molded article is Example Preparation and properties of No, polyoxymethylene copolymer R( "/1 90 minutes Poly-acetal composition Heat stability whiteness value, Z

A mixture of trioxane and styrene was irradiated with 'yrays of Co at 0C in a dosage of 1.2 X and then was subjected to a post- 59 polymerization at C for 8 hours, whereby a copolymer was obtained. The copolymer was then further acetylated with acetic anhydridc, The eopolymer had about 3 "/1 styrene content. an intrinsic viscosity of 2. l0 and K of (L06v A mixture of trioxane and acrylamide was irradiated with -y-rays of Co" at 0C in a dosage of [.2 X 10 and then was subjected to a postpolymerization at 50C for 8 hours, whereby a copolymer having an intrinsic viscosity of 1.80 and K of 004 was obtained. Trioxanc and dioxane were polymerized at 66C for 4 hours with boron fluoride etheratc. and the thus obtained copolymer was dissolved in 6| benxyl alcohol containing 10 tributylamine at 45C to remove unstable terminal units. The copolymer contained 2 /1 dioxolane and had an intrinsic viscosity of 1.90 and K of0.0l. A copolymer obtained by copolymerization of formaldehyde and dioxolane was dissolved in benzyl alcohol containing 10 "/1 tributylamine at U (12 [45C to remove unstable terminal units. The

copolymer contained Li /1 by mole of dioxolane and had an intrinsic viscosity of 1.90 and K.,..., of (L0l.

Example 63 200 parts of dimethyladipate 200 parts of hydrazine hydrate (purity: percent) and hexamethylene diamine, and 600 parts of urea are placed in a stainless steel autoclave provided with a stirrer and subjected to reaction at l80C under an autogencous pressure for 180 minutes After the reaction, the autoclave is cooled to 70C, and the temperature is again gradually elevated. while passing a nitrogen gas through the autoclave. Finally, the mixture is subjected to reaction at 200C for minutes. Then, the autoclave is subjected to pressure reduction down to 2 mm Hg, and is heated to 210C for 240 minutes to complete the reaction, whereby 580 parts of colorless, transparent, nitrogen-containing polycondensate having a nitrogen analysis of 25.36 percent is obtained. The resulting polymer can be molded into a film by pressing the same at C under a pressure of 250 kg/cm by-means of a test hot press.

Polyoxymethylene diacetate having an intrinsic viscosity of 1.80 and K of 0.04 is well mixed with 1.0 percent of said nitrogen-containing polycondensate,

99.00 and the whiteness value, Z is 99.

3 5 Examples 64-69 Various kinds of diearboxylic acid dihydrazides, di-

45 whereby nitgrogen-containing polycondensate is obtained.

Polyoxymethylene diacetate having an intrinsic viscosity of 2.00 and K222 of 0.05 is well mixed with 0.8 percent of said nitrogen-containing polycondensate,

50 0.1 percent of 4,4-dihydroxydiphenyl'2,2-propane and 0.3 percent of 2,6-di-tert.butyl-4methylphenol and the resulting polyacetal composition is extruded at a cylinder temperature of 195C by means of a small test extruder having a cylinder inside diameter of 20 mm to pelletize the same. The thus obtained pellets are sub- 0.3 percent of l,l,3-tris(2-methyl-4-formyloxy-5 jectcd to the heat stabilization test. The results are tert.butylphenyl) butane and 0.1 percent of 4,4- shown in Table 6.

Table 6 Components of charged Polyacetal composition ('4 by mole) composition Example Dicarboxylic acid Diamine Urea or Yield Soften whiteness No, dihydrazide urea dc- ('71 J ing Appearance RU/z) value.

rivatives point Z 64 Terephthalie Hexa- Urea 50 5X Hill-" colorless. 98.90 98 acid dimethylene transparent hydrazide 30 diamine 20 Table 6 Continued Components of charged Polyacctal composition 7! by mole) c iti Example Dicnrhoxylic acid Diaminc Urea or Yield Softenwhiteness No. dihydrazide urea de- ('7!) ing Appearance RUK value.

rivatives point 2 65 Naphthalene Ethylcnc- Biurea colorless,

dicarhoxylic diaminc 55 48 l90-200 transparent 98.80 )8 acid dihydrazide 66 Decamethylenc lso- Urea 34 50 l20-l40 colorless. 99.40 99 dicarboxylic phoronetransparent acid didiamine 33 hydrazide 33 67 Octadccanc- Polyethyl- Urea 62 70-90 slightly 98.62 98 l .l8-dicncimine yellow. carboxylic having semiacid dimolecular transparent hydrazide 40 weight of 600 20 68 Eicosane-l.20- Hexa- Urea 40 60 40-85 colorless 98.89 99 dicarboxylic methylenetransparent acid didiamine l5 hydrazidc 69 Sehacic acid Hexa- Ethylene 61 l 10-135 slightly 98.73 98 dihydrazide 30 methylene urea 25 yellow.

diaminc 20 Thiourea semi- 25 transparent Examplc 70 25 mate and 0.08 percent of 4,4'-dihydroxydiphenyl-2,2- v i amounts f 2 2' 4 1 propane, and then the mixture 15 mixed for 20 minutes tertbutylphenol) and 4 4' i 2 2 in a double cone blender and is vacuum-dried at C propane are dd d to h same polymer as i E l for 6 hours. Then, a molded plate having a thickness of l and then, the heat stability and resistance to light are 30 mm P p y a test hot Press at a temperature measured as in Example 1. The results are shown in of 190C, and Subjected to measurement of the heat Table 7 stability and resistance to light. The results are shown Table 7 Polyester 2,2'-methylene-bis-(4- 4,4-dihydroxy- R Resistance amide methyl-6-tert.butyldiphenyl-2.2- (/e) to light (C) phenol) propane 0.3 0.5 0.] 98.7 No change 9 0.5 0. I 99.0 No change L0 2.5 0.1 99.2 No Change 1.0 0.2 0.] 98.8 No change I. 0.5 2.5 99.] No change Example 71 in Table 8 together with the results of comparative Polyoxymethylene copolymer containing 3.1 percent tests- Table 8 No. Name of additive compound Amount of R(/( Resistance additive to light added (phr) Example 2.2-methylene-his-(4- 0.3 99.4 No change 7 l methyl-6-tcrt.hutylphenol) 4.4'-dihydroxydiphenyl- 0.08

Ill-propane polyester amide (C) 0.5 Compara- 2 2'-mcthylenc-his-(4- 0.38 91.3 No change tivc methyl-o-tert.butylphcnol 1 test I Compura- 4.4'-dihydroxydiphenyl- 0.38 87.5 No change tive 2.2-propanc test 2' Compara- Polyester amide (C) 0.5 85.0 No change tivc test 3' Compura- 2,2'mcth \'lene-bis-(4- 038 97.4 No change tive methyl-6-tc rt.hutylphenol) test 4' Polyester amide (C) 0.5 Compara- 4.4'-dihydroxydiphcnyl- 0.38 95.0 No change tivc 2 2-propane test 6' Polyester amide (C) 0.5

of the monomer units derived from dioxolane is mixed What is claimed is: with 0.6 percent of polyester amide (C), 0.3 percent of l. A polyacetal composition comprising, in admix- 2,2-mcthylene-bis-(4-methyl-6-tert.butylphenol) forture,

25 26 a a polyacetal. 01-! b 0.00] to 3 percent by weight. based on the weight of polyacetal, of a hindered phenolic antioxidant in y which at least one hydrogen atom at a position ortho to the phenolic hydroxyl group is substituted b an alk l mu c 0. l to ger cent by weight, based on the weight of C Z' polyacetal. of a nitrogen-containing compound selected from the group consisting of R a. a polyamide l0 7 7 b. A polyconden sate of dicarboxylic acid hydrazide. or a substance capable of yielding dicarboxa R OH ylic acid hydrazide, and urea and an aliphatic di- 0d 7 7 z dri '5 wherein R is alkyl of] to 5 carbon atoms, or the formate thereof.

4. A polyacetal composition of claim 1, wherein said hindered phenolic antioxidant is a compound of the d. an amidine, e. a cyanoguanidine, f. a polyurethane,

g. a polyurea, and formula h. a polyaminotriazole; and d. 0.001 to 3 peicent, based on the weight of polyace- F tal of 4,4'-dihydroxydiphenyl or a bisphenol com- 3 3" 0 pound having the formula:

7 1 2 H0 (C rl 0 CH C l t i r 3 H C OH 4 wherein R is alkyl of 1 to 5 carbon atoms, and R x is an integer of 1 to 6, or the formate thereof.

3 5. A polyacetal composition of claim 4, wherein x is wherein R and R are each independently hydrogen or 2. alkyl of l to 6 carbon atoms, or form a saturated homo- 6. A polyacetal composition of claim 1, wherein said cyclic ring. hindered phenolic antioxidant is a compound of the 2. A polyaeetal composition of claim 1, wherein said formula (CH C\ V R C(CH HO G CH vi 011 G01 V R10 R 9 CH2 R c(ca R OH 3 3 1O hindered phenolic antioxidant is a compound of the wherein formula R is hydrogen or methyl, and

01-1 OH Rm is hydrogen or alkyl of l to 4 carbon atoms.

7. A polyacetal composition of claim 1, wherein said hindered phenolic antioxidant is a compound of the CH formula 1 R ana c CH NHR R5 Ho H 6 R6 R 6 12 wherein R is hydrogen or alkyl of l to 3 carbon R H CH NHR 11 2 2 11 atoms; and

R is alkyl of l to 5 carbon atoms or the formate wherein thereof. R is hydrogen, alkyl of l to 5 carbon atoms or alke- 3. A polyacetal composition of claim 1, wherein said nyl of 3 to 4 carbon atoms; and hindered phenolic antioxidant is a compound of the R is alkylideneof l to 8 carbon atoms, or the formate thereof.

formula 3,903,197 27 I 28 8. A polyacetal composition of claim 1, wherein said hindered phenolic antioxidant is a compound of the formula c -CH2-CHCH3 X 10 wherein 7 R is alkyl of l to 5 carbon ab ms; and X is hydrogen, hydroxy, or alkyl of l to 5 carbon i O i2 R 6H atoms, or the formate thereof. 9. A polyacetal composition according to claim 1, [5

wherein said bisphenol compound is 4,4'-dihydroxydiwherein Phenylmethane. R is alkyl of l to 5 carbon atoms, or the formate [0. A polyacetal composition according to claim 1, thereof I i I wherein said bisphenol Compound is 4,45 19. A polyacetal composition of claim 16, wherein dihydroxydipphenyl l,Lethang said hindered phenolic antioxidant is a compound of 11. A polyacetal composition according to claim 1, the formula wherein said bisphenol compound is 4,4- dihydroxydiphenyll l -propane. 0 12. A polyacetal composition according to claim 1, 3 3 wherein said bisphenol compound is 4,4'-dihydroxydiphenyl-l,l-butane. H HO (C 2 C 13. A polyacetal composition according to claim 1, x X 2 wherein said bisphenol compound is 4,4- dihydroxydiphenyll l -heptane. R

14. A polyacetal composition according to claim 1, 3O 8 wherein said bisphenol compound is 4,4f-dihydroxydiphenol-2,2-propane.

15. A polyacetal composition according to claim 1,

wherein said bisphenol compound is 4,4-dihydryoxydi- I wherein i phenol-2-butane. R is alkyl of l to 5 carbon atoms, and

16. A polyacetal composition according to claim ,1, x is an integer of l to 6, or the formate thereof. wherein said nitrogen-containing compound is a poly- 20. A polyacetal composition of claim 19, wherein X amide. is 2.

l7. -A polyacetal composition of claim 16, wherein 21. A polyacetal composition of claim 16, wherein said hindered phenolic antioxidant is a compound of 40 said hindered phenolic antioxidant is a compound of the formula i the formula R C CH (CH C 9 H on R R R 9 C 2 9 l0 l0 C(CH 10 H 3 3 OH wherein V R, is hydrogen or methyl, and R is hydrogen or alkyl of l to 4 carbon atoms.

said hindered phenolic antioxidant is a compound of the formula wherein R is hydrogen or alkyl of l to 3 carbon atoms; and R HNH 0 R is alkyl of l to 5 carbon atoms, or the formate 2 thereof. HQ 18. A polyacetal composition of claim 16, wherein i said hindered phenolic antioxidant is a compound of R C the formula 11 2 22. A polyacetal composition of claim 16, wherein,

wherein R is alkyl of l to carbon atoms; and X is hydrogen, hydroxy, or alkyl of l to 5 carbon atoms, or the formate thereof. 24. A polyaeetal composition according to claim 16,

wherein said bisphenol compound is 4,4'-dihydroxydiphenylmethane.

25. A polyaeetal composition according to claim 16, wherein said bisphenol compound is 4,4'-dihydroxydiphenyll l -ethane.

26. A polyaeetal composition according to claim 16, wherein said bisphenol compound is 4,4-dihydroxydiphenyl l l-propane.

27. A polyaeetal composition according to claim 16, wherein said bisphenol compound is 4,4'-dihydroxydiphenyl-l, 1-butane.

28. A polyaeetal composition according to claim 16, wherein said bisphenol compound is 4,4-dihydroxydiphenyll l-heptane.

29. A polyaeetal composition according to claim 16, wherein said bisphenol compound is 4,4-dihydroxydiphenyl-2, 2-propane.

30. A polyaeetal composition according to claim 16, wherein said bisphenol compound is 4,4-dihydroxydiphenyl-2, 2-butane.

31. A polyaeetal composition of claim 16 wherein said polyamide is a homopolyamide, a polyester amide, a polyamidc urea or a polyurethane amide. 

1. A POLYACETAL COMPOSITION COMPRISING, IN ADMIXTURE, A A POLYACETAL, B 0.001 TO 3 PERCENT BY WEIGHT, BASED ON THE WEIGHT OF POLYACETAL, OF A HINDERED PHENOLIC ANTIOXIDANT IN WHICH AT LEAST ONE HYDROGEN ATOM AT A POSITION ORTHO TO THE PHENOLIC HYDROXYL GROUP IS SUBSTITUTED BY AN ALKYL GROUP, C 0.1 TO 10 PERCENT BY WEIGHT, BASED ON THE WEIGHT OF PLOYACETAL, OF A NITROGEN-CONTAINING COMPOUND SELECTED FROM THE GROUP CONSISTING OF A. A POLYAMIDE B. A POLYCONDENSATE OF DICARBOXYLIC ACID HYDRAZIDE, OR A SUBSTANCE CAPABLE OF YEILDING DICARBOXYLIC ACID HYDRAZIDE, AND UREA AND AN ALIPHATIC DIAMINE, C. A URACYL, D. AN AMIDINE, E. A CYANOGUANIDINE, F. A POLYURETHANE, G. A POLYUREA, AND H. A POLYAMINOTRIAZOLE, AND D. 0.001 TO 3 PERCENT, BASED ON THE WEIGHT OF POLYACETAL OF 4,4'' -DIHYDROXYDIPHENYL OR A BISHENOL COMPOUND HAVING THE FORMULA:
 2. A polyacetal composition of claim 1, wherein said hindered phenolic antioxidant is a compound of the formula
 3. A polyacetal composition of claim 1, wherein said hindered phenolic antioxidant is a compound of the formula
 4. A polyacetal composition of claim 1, wherein said hindered phenolic antioxidant is a compound of the formula
 5. A polyacetal composition of claim 4, wherein x is
 2. 6. A polyacetal composition of claim 1, wherein said hindered phenolic antioxidant is a compound of the formula
 7. A polyacetal composition of claim 1, wherein said hindered phenolic antioxidant is a compound of the formula
 8. A polyacetal composition of claim 1, wherein said hindered phenolic antioxidant is a compound of the formula
 9. A polyacetal composition according to claim 1, wherein said bisphenol compound is 4,4''-dihydroxydiphenylmethane.
 10. A polyacetal composition according to claim 1, wherein said bisphenol compound is 4,4''-dihydroxydipphenyl-1,1-ethane.
 11. A polyacetal composition according to claim 1, wherein said bisphenol compound is 4,4''-dihydroxydiphenyl-1,1-propane.
 12. A polyacetal composition according to claim 1, wherein said bisphenol compound is 4,4''-dihydroxydiphenyl-1,1-butane.
 13. A polyacetal composition according to claim 1, wherein said bisphenol compound is 4,4''-dihydroxydiphenyl-1,1-heptane.
 14. A polyacetal composition according to claim 1, wherein said bisphenol compound iS 4,4''-dihydroxydiphenol-2,2-propane.
 15. A polyacetal composition according to claim 1, wherein said bisphenol compound is 4,4''-dihydryoxydiphenol-2-butane.
 16. A polyacetal composition according to claim 1, wherein said nitrogen-containing compound is a polyamide.
 17. A polyacetal composition of claim 16, wherein said hindered phenolic antioxidant is a compound of the formula
 18. A polyacetal composition of claim 16, wherein said hindered phenolic antioxidant is a compound of the formula
 19. A polyacetal composition of claim 16, wherein said hindered phenolic antioxidant is a compound of the formula
 20. A polyacetal composition of claim 19, wherein x is
 2. 21. A polyacetal composition of claim 16, wherein said hindered phenolic antioxidant is a compound of the formula
 22. A polyacetal composition of claim 16, wherein said hindered phenolic antioxidant is a compound of the formula
 23. A polyacetal composition of claim 16, wherein said hindered phenolic antioxidant is a compound of the formula
 24. A polyacetal composition according to claim 16, wherein said bisphenol compound is 4,4''-dihydroxydiphenylmethane.
 25. A polyacetal composition according to claim 16, wherein said bisphenol compound is 4,4''-dihydroxydiphenyl-1,1-ethane.
 26. A polyacetal composition according to claim 16, wherein said bisphenol compound is 4,4''-dihydroxydiphenyl-1, 1-propane.
 27. A polyacetal composition according to claim 16, wherein said bisphenol compound is 4,4''-dihydroxydiphenyl-1, 1-butane.
 28. A polyacetal composition according to claim 16, wherein said bisphenol compound is 4,4''-dihydroxydiphenyl-1, 1-heptane.
 29. A polyacetal composition according to claim 16, wherein said bisphenol compound is 4,4''-dihydroxydiphenyl-2, 2-propane.
 30. A polyacetal composition according to claim 16, wherein said bisphenol compound is 4,4''-dihydroxydiphenyl-2, 2-butane.
 31. A polyacetal composition of claim 16 wherein said polyamide is a homopolyamide, a polyester amide, a polyamide urea or a polyurethane amide. 